The present invention relates to an angled opto-mechanical connector and to a production method for the same.
In order to reduce the total cost for connecting optical fibres, multifibre contacts are used. The advantage of these are that the time-demanding and thereby expensive mounting and subsequent working stages can be performed on several fibres at the same time. Several embodiments of multifibre connectors are known.
One of these is the Japanese so-called MT-connector. It is based on a precision part made of extruded thermoplastic in which the fibres are mounted (glued).
In another embodiment of multifibre connectors, an MT-compatible optical connector is directly extruded onto the fibres, see Swedish Patent Application 9301858-8. The fibres and guide pins are placed and fixed in V-grooves in the mould cavity itself after which the extrusion takes place. The method means that the gluing step disappears which rationalizes the production and is expected to lower its costs. It does, however, place a requirement for high precision in the mould cavity.
A further method is to use small precision parts, so-called fixtures, as micromechanical supporting elements. The precision parts can be produced in e.g. silicon, whereby a number of these can be obtained from a disc of silicon which can give a low manufacturing cost. The precision parts position the fibres and the guide pins in relation to each other and are cast into the connector. This permits the precision requirement of the mould cavity to be reduced considerably.
As optical short-haul links become more competitive in relation to electrical short-haul links, they will be used in existing equipment practice. In order that electrical and optical components can coexist in traditional board-wiring side equipment practice and thereby improve the chances for cost-effective total solutions, several new optical components are required. One of these is the so-called right-angle connector. An object of such a right-angle connector can be to provide a space-saving optical connection between the circuit board and the board-wiring side.
In GB 2 256 286 a bending module for optical fibres is described which comprises a two-part casing which defines a channel for the fibre. The bending module can be mounted onto a plate. The bending module is, however, not intended for fibre ribbons but only for single fibres.
The object of the present invention is to achieve an angled optical connector for fibre ribbons which can be quickly and easily connected, for example between circuit boards and the board-wiring side, and which gives a very low damping. The connector should have high mechanical precision and furthermore be simple and cheap to manufacture.
This is achieved by using a precision part as a micromechanical supporting element. The precision part is manufactured with grooves for fibres and guide pins. A lid is attached onto the precison part and the fibres and guide pins are positioned in respective grooves. An angled capsule is subsequently produced in a mould cavity intended for that purpose.
The precision part or fixture has straight and parallel grooves running on the upper side of the fixture from a first fixture side to a second fixture side, which grooves are intended partly for optical fibres from e.g. a fibre ribbon cable and partly for guide pins. A lid is fastened above the fixture, for example through anodic bonding. Peeled fibre ends from a fibre ribbon are placed in the grooves intended for the fibres so that the fibre ends stick out through the second fixture side. Guide pins are introduced into the grooves intended for the guide pins. They can stick out through both the first and the second fixture sides.
This structure (fixture, lid, fibre ends and guide pins) is completely or partially surrounded by a capsule, made, in particular, of plastic. The fibre ribbon sticks out from the capsule on the rear side. The fixture is so positioned that the fibre ribbon is bent through a predetermined angle in the plastic capsule.
In an alternative embodiment a second precision part with lid and guide pins is mounted at the other end of the fibre ribbon which consequently in this case is also peeled. The structure obtained (fibre ribbon with fixture, lid and guide pins mounted at each end of the fibre ribbon) is completely or partially surrounded by a capsule, made, in particular, of plastic. The two fixtures are so positioned that the fibre ribbon is bent through a predetermined angle in the plastic capsule.
Preferably, the fibres are bent through an angle of 90 degrees in the capsule but also other angles are possible, e.g. 180 degrees. The fibre ends can be polished.
The second side of the fixture can be covered by plastic which makes any necessary polishing easier. By using suitable shaped opposing means (e.g. with bevellings) in the mould cavity which give an impression with markings, the distance to the second side of the fixture can be more easily matched during polishing.
One advantage of the present invention is that the connector can be quickly and easily connected and has high mechanical precision. It is furthermore simple and cheap to manufacture.
Another advantage of the present invention is that the precision requirements on the mould cavity are considerably reduced when micromechanical supporting elements are used. The manufacturing in this way becomes more rational.
Yet another advantage of the invention is that the cast-in fixture functions as an anchor in the plastic and simplifies the fixing of the fibres.
A further advantage is that if the connector is moulded onto the fibres and fixtures (i.e. if the fibres do not need to be glued), then the manufacturing is simplified and made cheaper.
Moreover, any necessary polishing becomes easier if the second side of the fixture is covered by plastic and consequently only a combination of fibres and plastic need to be polished. By using opposing means which give an impression with markings, the distance to the second side of the fixture can be matched during polishing.